Slide clamps are used frequently in hospitals to control fluid flow in compressible medical tubing such as, for example, flexible polyvinyl chloride tubing commonly employed in infusion pump sets and parenteral administration sets to deliver drugs, medicament, blood, dextrose solution or other medical fluids to a patient's venous system.
Slide clamps of the foregoing type have been used to adjust fluid flow at different flow rates between full flow and no flow, but they are principally employed as on/off clamps, i.e., to totally occlude the tubing lumen to shut off fluid flow entirely, or to allow for unrestricted fluid flow, without occluding the tubing lumen.
A principal disadvantage inherent with slide clamps used with infusion pumps or parenteral administration sets is that it is difficult to position the clamp and have it remain at a selected point on the tubing length when in the full-flow, or on, position. More often than not, the clamp will slide down the tubing to another location and because of its relatively small size it is difficult to locate immediately. Thus, when a nurse or other operator desires to utilize the clamp to occlude the tubing lumen, precious time must be taken to search for the slide clamp. This is especially so when the infusion pump or administration set, as is often the case, includes many other elements, such as roller clamps, needles, filter housings, check valves, drip chambers and the like.
The infusion pump or administration set is usually disposed substantially vertically, between an infusion pump or a solution container at its upper end and a patient's arm or other venous access site at the lower end. Thus, as the infusion pump or administration set is set up between the solution source and the patient, a slide clamp on the tubing is jostled so that it falls until it rests upon one of the other elements in the set.
The search for the slide clamp is time consuming and bothersome. Once found, the operator will move the slide clamp along the length of tubing to an elevation which does not interfere with any other set element and which is also convenient for use by the operator. Once this is done, the operator will close the slide clamp. However, the slide clamp will usually be reemployed by sliding it along its slot from the lumen occluding "off" mode back to the "on" mode. When the slide clamp is readjusted to the "on" mode, it will once again slide down the tubing, making necessary a still subsequent search if it is to be used again.
Attempts have been made to solve this problem, as shown in U.S. Pat. No. 2,889,848 to Redmer. Redmer employs a two piece structure including a slide-type clamp, in conjunction with a clamp body section or block. The Redmer clamp is designed for being maintained at a given elevation while in the on position by carefully dimensioning the block bore to the tubing diameter. Thus, the Redmer clamp may be used with essentially only one tubing size. Also, the Redmer clamp is relatively expensive to manufacture. One of the key advantages of slide clamps is that they are inexpensive. If the cost of a slide clamp is too great, other devices, such as roller clamps, can easily be used.
In U.S. Pat. No. 4,434,963 issued to Russell, a slide clamp is disclosed which purportedly addressed the above disadvantages. This slide clamp includes a stabilizer which together with cocking or angular tilting of the clamp on the tubing permits the clamp to remain at the selected elevation. The Russell clamp remains problematic because in actual practice the clamp does slide down the tubing during use and abuse by the attending staff, particularly when the clamp is not tilted.
Another disadvantage of many known slide clamps is that they must be installed during manufacture as opposed to being added by a nurse or other operator during use. Further, the clamp cannot be removed if desired. The clamp shown in Redmer and Russell may be added or removed at the time of use but the former necessitates keeping track of two separated pieces and suffers from the other disadvantages discussed above. Nevertheless, Redmer and Russell have proven to be ineffective attempts at maintaining slide clamps at the desired elevation on tubing.